Thermal hand tools

ABSTRACT

The present invention relates to a group of hand thermal tools of simplified construction wherein each has the same upper and lower hand grip members hinged together adjacent to their rear ends and moreover the upper and lower grip member may be identical. A power lead line, extending in at the rear of the grip members, powers each tool. The three distinct thermal hand tools contemplated are; resistance tweezers, conductive tweezers, and wire stripper. The resistance tweezers has a single conductor rod in each grip member extending the length thereof and a tweezer blade removably mounted at the forward end of each rod whereby an electrically conductive object tweezed between the blades becomes resistance heated. The conductive tweezers and the thermal wire stripper each utilize a pair of conductive rods in each grip member extending the length thereof and a resistance heated blade member mounted across the forward ends of each rod pair. In the conductive tweezer, a gripping blade is removably mounted across the forward ends of each rod pair, the blades being opposed so that an object tweezed therebetween becomes heated by thermal conductivity. In the wire stripper, a cutting blade is mounted across the forward end of each rod pair, the blades being in opposing cutting relationship whereby an insulated wire may have the insulation stripped therefrom by the cutting action of the heated blades.

United States Patent [19] Lloyd et a1.

[ THERMAL HAND TOOLS [75] Inventors: Richard E. Lloyd, Beltsville;Loring E. Young, Frederick; William J. Siegel, Silver Spring, all of Md.

[73] Assignee: Pace Incorporated, Silver Spring,

Md. by said Lloyd and Young 221 Filed: Apr. 8, 1971 211 App]. No.:132,499

Related U.S. Application Data [63] Continuation-impart of Ser. No.41,325, May 28,

1970, abandoned.

[52] U.S. CI. 81/9-5 B, 219/221, 219/234 [51] Int. Cl. H02g l/12 [58].Field of Search 81/9.5 B, 9.5 R,

FOREIGN PATENTS OR APPLICATIONS 91 1,957 4/1946 France 219/234 1,065,4011/1954 France 219/225 1,046,133 12/1958 Germany 81/9.5 B

[451 Aug. 114, 1973 Primary Examiner-Robert C. Riordon AssistantExaminer-Roscoe V. Parker Attorney-Fide1man, Wolffe & Leitner STRACT Thepresent invention relates to a group of hand thermembers, powers eachtool. The three distinct thermal hand tools contemplated are; resistancetweezers, conductive tweezers, and wire stripper. The resistancetweezers has a single conductor rod in each grip member extending thelength thereof and a tweezer blade removably mounted at the forward endof each rod whereby an electrically conductive object tweezed betweenthe blades becomes resistance heated. The conductive tweezers and thethermal wire stripper each utilize a pair of conductive rods in eachgrip member extending the length thereof and a resistance heated blademember mounted across the forward ends of each rod pair. In theconductive tweezer, a gripping blade is removably mounted across theforward ends of each rod pair, the blades being opposed so that anobject tweezed therebetween becomes heated by thermal conductivity. Inthe wire stripper, a cutting blade is mounted across the forward end ofeach rod pair, the blades being in opposing cutting relationship wherebyan insulated wire may have the insulation stripped therefrom by thecutting action of the heated blades.

4 Claims, 30 Drawing Figures Patented Aug. 14, 1973 3.752,017

6 Sheets-Sheet 1 Patented Aug. 14, 1973 6 Sheets-Sheet 3 Patented Aug.14, 1973 6 Sheets-Sheet 5 Patented Aug. 14, 1973 6 Sheets-Sheet 4 I) 11A}; f

Patented Aug. 14, 1973 3,752,017

6 Sheets-Sheet 5 Patented Aug. 14, 1973 6 SheetsSheet 6 a MN VII/l/I/l4. \W

Um rllllllllllf l NNN THERMAL I-IANI) TooLs tries faces certain severeproblems. To make repairs of a quality consistent with that of originalmanufacture, he requires sophisticated specialized hand tools. Yet,truly skilled electronic repair technicians are so few they represent aminiscule market for the manufacturer of such tools. In consequence,tools for electronics repair technicians are expensive, are often poorlyconstructed, and frequently represent a compromise between tool qualityand manufacturing costs. The manufacturer is in a poor position. Can hejustify a substantial investment in a specialized hand tool when, afterall has been done, the sales potential may be inadequate to covermanufacturing and sales costs with enough profit to recoup developmentexpenses).

The problem facing both the repair technician customer and manufacturercan be eased by grouping several diverse hand tools into a singlemanufacturing entity, as has been done in the present invention, so thatthe total sales potential of the entity is greater. The presentinvention, then, makes high quality hand tools available at prices whichshould satisfy customer and manufacturer alike.

The present invention provides three distinct and separate specializedtools to the repair technician; a conductive tweezers, a resistancetweezers and a thermal wire stripper. These hand tools are notconvertable one to another. A properly equipped electronics repairtechnician should have all three tools. However, all three tools containmany common components, and overall, are so similar that they constitutea Single entity, from the manufacturers viewpoint. In particular, thehand grip members present in each of the three tools are the same.Moreover, in a preferred embodiment, the hand grips are constructed sothat the upper and the lower hand grip members in each tool areidentical. Accordingly, the manufacturer of these tools can expect a farlarger demand for the component elements he must obtain by manufactureor purchase. Specifically, he may count on as much as a six-foldincrease in his needs for the grip member, even if sales for each Iindividual hand tool is no greater than heretofore. High volumemanufacturing techniques may be employed, such as for example formingthe grip member as a molded plastic element. Unit costs are diminishedsubstantially, higher quality specialized tools can be manufactured atcompetitive prices.

For further understanding of the present invention, reference is nowmade to the attached drawings wherein:

FIGS. 1, la and 1b are isometric views showing the three thermal toolsside by side;

FIG. 2 is a top plan view of the wire stripper (in closed position);

FIG. 3 is a side view of the wire stripper in an open position;

FIG. 4 is an inside view of one of the grip members taken along line 4-4of FIG. 3;

FIG. 6 is a front view of the wire stripper in closed position;

FIG. 7 is a rear view of the wire stripper in closed position;

FIG. 8 is a section taken along line 8-8 of FIG. 2;

FIG. 93 is a section taken along line 9-9 of FIG. 2;

FIG. 10 is a section taken along line 10-10 of FIG. 2;

FIG. 11 is a section taken along line 11-11 of FIG. 2;

FIG. 12 is a view similar to FIG. 4 only taken through the median lineof the conductive tweezers;

FIG. 13 is a side section similar to FIG. 5 of the conductive tweezers;

FIG. 14 is a circuit diagram of the electrical connections in thethermal wire stripper;

FIG. 15 is a fragmentary perspective of the wire strippers strippingwire;

FIGS. 16 and 17 illustrate various modes of conductive tweezer blades; 7

FIGS. 18 and 19 are fragmentary views illustrating how the conductivetweezer blades grip the objects tweezed therebetween;

FIG. 20 is a view similar to FIG. 4 taken along the median line of theresistance tweezers;

FIG. 21 is a side section similar to FIG. 5 of the resistance tweezers;

FIG. 22 is a front end section taken along line 22-22 of FIG. 20;

FIG. 23 is an enlarged exploded view of the collet structure at theforward end of the resistance tweezers;

FIG. 24 illustrates several modes of resistance tweezer blades; I

FIG. 25 illustrates the cross-sectional shape of several modes ofresistance tweezer blades; and

FIGS. 26., 27, and 28 illustrate how the resistance tweezer blades maygrip an object therebetween.

As may beseen in the drawings, and in particular in FIGS. I, la and 1b,the wire stripper 1, the conductive tweezers 5, and the thermalresistance tweezers 10, shown respectively in FIGS. 1, 1a, and lb, arethree diverse hand thermal tools. Their construction does not permitconversion of one tool into another. A well equipped skilled electronicsrepair technician should have all three tools. Yet, their constructionis essentially the same. This will be further illustrated during thedetailed description of the individual toolswhich follows; theinterchangeable component elements are identified by the same numeralsin all three tools.

All three tools include a pair of hand grip members 12 and I4 hingedtogether by a hinge pin 16. In the preferred embodiment illustrated inthe drawing, hand grip members 112 and M are identical in structure.

The grip member 12 or 14 is formed with a front end portion thereof as aU-shaped channel 11 with a channel bottom 13 wide enough to seat a pairof spaced conductor rods 22,24. Side walls 15 essentially conceal theconductor rods. The base end portion 17 of the grip memberhas anexternal flange 19 on one side and an internal flange 21 on the otherside. As may be seen in FIG. 11, when a pair of grip .members 12,14 areassembled, the external flange 19 will overlie internal flange 21. Hingepin 16, which secures grip members 12,14

FIG. 5 is a side section taken along line 5-5 of FIG.

together'cxtends through apertures in flanges i9 and 21 and the bosses21 in each grip member. For better operation of the hinge member spacers23 are provided and located between internal flanges 21 and bosses 21'.Just forward of hinge pin 16 (See FIG. 10) is a well 72 in which seats aspring 70 to urge the hand grips into a spread-apart position (shown inFIGS. 5 and 8). For electrical connection purposes, the rear face 25 ofthe grip member contains a circular aperture which leads into passageway53. The grip members fit together well.

Normally, the grip member will be a molded plastic piece, e.g., carbonblack and fiberglass filled nylon. The molds are relatively expensive.Use of the same grip members for several tools spreads the mold expenseover more units and permits utilization of molded plastic grip membersfor such low volume products as the handtools of the present invention.The above described preferred grip identity necessitates only one set ofmolds for three tools.

In thermal wire stripper 1, a pair of elongated conductor rods 26 and 28are concealed within the hand grip 12 resting in and secured to channelbottom 13 at the underside of grip 12. Conductor rods 22 and 24 restwithin and are secured to grip member 14 also being largely concealed bythe depending (or upstanding) side walls 15 of the hand grip member. Theconductor rods are fixed to the hand grip member by conventionalexpedients such as, for example, screw members 29 threaded throughrecessed holes in the rods and tapped holes in grip members 12 and 14.

' Mounted across the forward end face of rods 22 and 24 is acutter blademember 30, the blade being removably secured thereon as for example byscrews 31 threaded into tapped recesses in the end faces of rods 22 and24 (as shown in FIG. 3). A like blade member 20 is mountedon the forwardend faces of rods 26 and 28. Blades 20 and constitute the wire strippingblade components-of thermal wire stripper l.

Advantageously, the conductor rods 22, 24, and 26, 28 also serve asguides for adjustable stop members 32, 33 and 34, which stop members,desirably, are of identical construction. Asshown in FIGS. 3 and 5,opposing stop members 32 and 34 contact each other to stop the gripmembers I2, 14 from closing fully. Normally, the.

length of wire insulation to be stripped.

As may be seen in FIGS. 5 and 8, the stop members, e.g., stop member 33is apertured or cut out at its base to fit the rods 22,24 and to slidethereon. Use of the hexagonal shaped rods illustrated in the drawingrequires a corresponding hexagonal multi-facet cutout on stops 32, 33,34, for the desired close fitting slide engagement. The top of each stophas a beveled surface and a horizontal surface 4]. Normally, stops 32and 34 are disposed in opposition so that closing motion of the grips l2and 14 brings the beveled surfaces 40 into engagement with blades 20 and30 spaced apart as shown in FIGS. 6 and 15. To repeat, thermal wirestripper 1 is constructed to strip insulation from a wire rather than tocut the wire. As may readily be appreciated, a shift in the position ofeither stop 32 or 34 will cause the beveled surfaces 40 to contacthigher or lower and thereby allow the closed position gap between blades20 and 30 to be closely predetermined.

The stops 32, 33 and 34 are constructed so that they may be locked inplace. As best illustrated in FIG. 8, it may be seen that the lowerportion of the stop 33 is split longitudinally leaving a gap from thebottom edge of the stop to some midpoint in the stop. A screw member 736 threaded into the side of stop 34 wedges the split or bifurcatedlower portions of the stop 33 apart, thus locking them to the rods 22and 24 by frictional engagement therewith. Partially unthreading screwmember 36 unbinds stop member 33 and it may thenslide as desired alongrods 22 and 24. Stops 32 and 34 are positioned according to the size ofthe wire being stripped to stop blades 20,30 short of severing the wire.The spacing stop member 33 is locked to*rods 24 and 22 at whateverdistance from blades 20 and 30 should be the measure for the length ofinsulation being stripped. The lead 38 is inserted past blades 20 and30, as shown in FIG. 15, until it contacts the forward face of stopmember 33, then the thermal wire stripper 10 is closed to sever theinsulation from the lead. The stop members 32, 34 and 33 areparticularly useful when a number of leads have to' be stripped to thesame length.

Electrical power for thermal stripper 10 is provided from a plug 50which extends into lower grip member 14 from the rear thereof passingthrough the aperture in rear face 25 into passage 53. This is apreferred alternative to a permanently attached power line at the rearof thermal stripper 10. The power line 51 is only a temporary attachmentto inlet plug 50 and thermal wire stripper 1. Lead lines 52, 54 extendinto grip member 12 from plug 50 being connected to rods 22 and 24 andalso by' leads. 56 and 58 to rods 26 and 28. The electrical connectionsare diagrammatically illustrated in FIG. 14.

Just forward of the wire connections to the rear of the conductor rods22, 24, 26 and 28, a pair of shield members 60 and 62 may be disposed ingrooves 61 and 63 of the grip members with shield 60 mounted on thelower rods 22 and 24 in groove 61 on grip 14 and shield 62 mounted onthe upper rods 26 and 28 in groove 63 of grip l2. Presence of shields60,62 is optional. The rods 22, 24, 26 and 28 conduct the electriccurrent which serves to resistance heat blades 20 and 30. To

repeat, the hand 'grip members 12 and 14 and shields 60 and 62 aremolded from insulating plastic, materials (such as hard rubber, nylonand the like) to protect the user.

Hand grip members 12 and 14 are biased apart by the soft compressioncoil spring seated in wells 72 just forward of hinge pin 16 (as shown inFIGS. 5 and 10). In passing, it may be noted that a leaf spring may besubstituted for coil spring 70. Such a spring might well extend betweengrip members 12,14 adjacent the path of wire lead 58 (see FIG. 5). Arear adjustment block (see FIGS. 2 and 3) limits the extent to which thegrip members 12 and 14 are sprung apart. The rear aperture and passage53 of upper grip member 12 contains a press fit insert 80 (FIGS. 3 and7) to which adjustment block 82 is secured, as for example by screwmember 84 threaded into insert 80. The position of screw 84 setsadjustment block 82 and predetermines how far apart the grips l2 and 14are spread by compression spring 70 or other spring means. Presence ofadjustment block 82 is advantageous, since the spread can be adjustedfor the lead to be stripped by wire stripper 1, or, in the instance oftweezer 5,10 for the size of the object tweezed.

The high degree of symmetry in the thermal wire stripper 1 isnoteworthy. Grip members 12 and 14 may of course be identical. Rods 22,24, 26 and 23 are identical. The stops 32, 33 and 34 are identical. Sotoo are shields 60 and 62 and blades and 30. Also noteworthy is thestructural simplicity of the tool; component parts may have a dualfunction. Thus, conductor rods 22, 24 and 26 and 28 serve both asconductors and as guide rods for stops 32, 33, 34.

The same grip members 12 and 14 and all associated structure includingspring 70, hinge pin 16, the adjustment block structure of members 80,82, 84, and even the bar stock from which conductor rods 22, 24, 26, 28are cut is the same in all three tools 1, 5, 10. This use of the samemajor components is illustrated in the side by side showings of FIG. 1,1a and lb.

The conductive tweezers 5 is structurally most like thermal wirestripper 1. It contains not only hand grips I2 and 14, but a pair ofsimilar conductor rods 122, 124 & 126, 128 in the grip member. Also, theelectrical connections to the rods are-the same as is shown in FIG. 14.Of course, wire stripper cutter blades 20 and 30 have been replaced byconductive tweezer blades 120 and 130. The principal difference betweenthe tools resides in the blade structure. In a preferred embodiment ofconductive tweezers 5, the conductive rods are not interchangeable withthose of wire stripper 1. However, the rods for each tool are formedfrom the same bar stock. FIGS. 16 and 17 illustrate various bladeshapes. One form of blade is shown as blades 102 and 130. A more highlycurved blade set 125 and 135 are illustrated in FIG. 16. FIG. 17 showsblade set 127, 137 and 129 and 139. FIG. 18 illustrates how blades 125and 135 may grip and conductively heat a pair of intersecting leads 132,134, to melt a soldered connection 136 apart. FIG. 19 illustrates howblades 120 and 130 can grip and heat a cylindrical wire lead 138.

Normally, the conductive tweezers would be provided with a full set ofdifferently sized and shaped conductive tweezer blades, including, forexample, all

' those illustrated in FIGS. 16, 17. Accordingly, conductive tweezer 5contains provision for re-placing the blades. As is shown in FIG. 12,the front face of each conductor is apertured to provide a blind openingtherein into which a base end of blade 120, for example, may beinserted. Set screws95 lock blade 120 to rods 126 and 128(The blindopening and set screw structure is provided in all four conductive rods122, 124, 126 and 128 to lock the conductive tweezer blades in thedesired opposing relationship.

Resistance tweezer It) differs from the other tools in that only oneconductor rod seats inside in each grip member. Thus, as may be seen inFIG. 21, single conductor rods 222 and 226 are mounted centrally of gripmember l2 and 14. The grip member is however the same as in the othertools, as are the various appurtenances thereto like spring 70, hingepin 16, plug 56, etc. The wiring is different since a connection to eachrod is all that is needed. Desirably, the molded grip member is madewith sets of three apertures 65, 66, 67

(which may be tapped) as shown in FIGS. 1, la and 1b, so that two rodsmay be mounted side by side using apertures 65, 67, as is the instancewith conductive tweezers 5 and thermal wire stripper 1, or one rod maybe mounted centrally using aperture 66 as is the instance withresistance tweezers 10.

In a preferred embodiment of resistance tweezer, the forward end of theconductor rods 222 and 226 is straight as illustrated in FIG. 21. Theresistance tweezer 10 is useful in any instance where the tweezed objectis metallic e.g., a connector pin, capable of being resistance heated tothe desired level by passage of current therethrough. However, somedanger of arcing exists with use of the resistance tweezer, and ininstances where arcing must be avoided, the conductive tweezer may bethe preferred tool.

In the instance of conductive tweezers 5, a set screw is used forattaching the blade to the conductive rods. The same may be done withthe resistance tweezer blades, but this structure is considered a lesspreferred embodiment than the collet structure illustrated in FIGS. 20through 23. The collet structure involves a rounded off forward endportion on the conductor rods 222 and 226 (shown in FIG. 23) and athreaded sectin 241 thereon. The forward end face of the rod is providedwith a slot 243 which extends rearwardly to threaded portion 241 andbeyond. The resistance tweezer blade is disposed inside the slot 243 andis locked thereon by threading collet 245 onto the threaded section 241.

If desired, slot 243 may be a composite slot so that various crosssection tweezer electrodes may be employed, 'i.e., the round, flat,square, half round, cross section shapes illustrated in FIG. 25. Apreferred shank end structure involves a tang 225 on each side of theblade. The tang structure locks the shank end of blades 223, 233 intothe composite slot 243. The forward end of the resistance tweezer bladesor electrodes also may be varied. Normally, a full set of differentblades would be provided with the resistance tweezers, including theflat and concave blades 223, 233 and 225, 235 illustrated in FIG. 24. Afull set of blades permits resistance tweezers 10 to grip varying leads138 and electrical lead connections 132, 134 in the manner illustratedin FIGS. 26, 27 and 28 to grip same and to resistance heat same bypassage of electric current therethrough. For example, a solderedconnection 136 might be grasped directly between the electrodes of theresistance tweezer and resistance heated until the solder melts; thewires can then be separated. The probable use of several differenttweezer blades during the course of a repair job is what makes thequicker release collet structure preferable to the set screw-structurecontemplated conductor rods are formed, etc. Indeed, only the blades andtheir mounting elements are specific to each tool.

All in all, a higher quality tool can be provided tothe repairtechnician than heretofore.

What is claimed is:

l. A thermal wire stripper comprising;

upper and lower insulated grip members hinged together adjacent the rearends thereof;

a pair of electrically conductive guide .rods disposed in each gripmember and extending forward of said grip member;

an electrically conductive blade member disposed stop block meansslidably mounted on the rods adjustably limiting the closest approachpermitted for the blade members.

2. A thermal wire stripper according to claim 1 including a stop blockslidably mounted on the rods in the lower grip member said stop blockhaving a beveled upper surface; and

an identical stop block slidably mounted on the rods of the upper gripmember, the engagement position of the beveled surfaces predeterminingthe closest approach permitted for the blades.

3. A thermal wire stripper according to claim 2 wherein a thirdidentical stop block is slidably mounted on one'of the rod pairsadjacent the blade end thereof, said third block serving as a spacerelement to predetermine the length of wire to be stripped.

4. A thermal wire stripper according to claim 1 wherein the grip membersare identical.

1. A thermal wire stripper comprising; upper and lower insulated gripmembers hinged together adjacent the rear ends thereof; a pair ofelectrically conductive guide rods disposed in each grip member andextending forward of said grip member; an electrically conductive blademember disposed across the forward end faces of each rod pair, theblades being in opposing cutting relationship; an electrical power leadconnection at the rear of said grip members connected to each rod pairto cause resistance heating of the blades; an adjustment means mountedat the rear of said members adjustably limiting the maximum openposition spread of said grip members; and stop block means slidablymounted on the rods adjustably limiting the closest approach permittedfor the blade members.
 2. A thermal wire stripper according to claim 1including a stop block slidably mounted on the rods in the lower gripmember said stop block having a beveled upper surface; and an identicalstop block slidably mounted on the rods of the upper grip member, theengagement position of the beveled surfaces predetermining the closestapproach permitted for the blades.
 3. A thermal wire stripper accordingto claim 2 wherein a third identical Stop block is slidably mounted onone of the rod pairs adjacent the blade end thereof, said third blockserving as a spacer element to predetermine the length of wire to bestripped.
 4. A thermal wire stripper according to claim 1 wherein thegrip members are identical.